Rim or long travel gripper assemblies are typically characterized by their relatively narrow width and long jaw travel, and having a wide range of applications in a limited space. For example, such grippers are useful for gripping tire rims and other objects. The movement of the jaw arms is controlled by their travel along a guide rail. Because of the rectilinear jaw motion, these grippers can be useful for both internal and external gripping applications. Actuation of the gripper is typically by a hydraulic or pneumatic piston assembly.
Manufacture of rim or long travel grippers involves machining metal parts including jaws and bases. Because typical grippers of this type require many air passages and bores, machining those passages is a preferred method of manufacture. This type of manufacture, however, can be costly and time consuming with the resulting structures being relatively heavy. In addition, such milled structures require additional components like bearing inserts in order to be complete.
It would be useful to provide, as one illustrative embodiment, an improved long travel gripper assembly that provides parallel-spaced jaw guides that are also collectively triangularly-positioned to provide a center of torsion for the actuation means of the gripper. The triangularly-positioned guide rail configuration makes for an inherently symmetric, and possibly stiffer and stronger structure than prior art designs. Because of the symmetry with respect to the piston rods, the center of torsion of the jaws is about coincident with the center line of the piston rod. Thus, twisting of the jaws will merely rotate them about the center line of the piston rod, rather than apply a torque or other force against the piston, rod, or other components which could sustain damage or wear prematurely. This design may also reduce the risk of leaking in the jaws by limiting distortion of the piston seals that would otherwise result as the piston bore is pushed laterally against the seal.
It would also be beneficial in other embodiments, to provide jaw arms and/or other components of the long travel gripper assembly that are manufactured through an extrusion process. This process may create the desired bores and shapes necessary for such structures, while decreasing the gripper's relative weight and cost.
Accordingly, an illustrative embodiment of the present disclosure provides a long travel gripper which comprises first and second end caps, first, second and third guide rails, first and second jaws, and first and second piston assemblies. The first, second and third guide rails extend between the first and second end caps and are positioned at parallelly spaced and at acute angles to each other. The first and second jaws, each receive, and move rectilinearly along, the first, second and third guide rails. The first piston assembly comprises a first piston rod and piston. The first piston rod is located between the first, second and third guide rails, wherein at least a portion of the first piston rod is disposed in a portion of the first jaw. The first piston is coupled to the first piston rod, is located in a cavity in the first jaw, and assists moving the first jaw. The second piston assembly comprises a second piston rod and piston. The second piston rod is located between the first, second and third guide rails, wherein at least a portion of the second piston rod is disposed in a portion of the second jaw. The second piston is coupled to the second piston rod, is located in a cavity in the second jaw, and assists moving the second jaw.
In the above and other illustrative embodiments, the long travel gripper may also comprise: the first piston rod being located at a center of torsion between the first, second and third guide rails, and the second piston rod being located at a center of torsion between the first, second and third guide rails; the first piston rod being coupled to the first end cap and the second piston rod being attached to the second end cap; a base that extends between the first and second end caps, wherein the base comprises at least one fluid passage longitudinally disposed there through, and wherein the base and the at least one fluid passage being formed via an extrusion process; a synchronizing assembly that synchronizes movement of the first and second jaws; a sensor assembly that detects positioning of the synchronizing assembly to determine positioning of the first and second jaws—the first piston further comprising first and second seals spaced apart from each other and disposed about the periphery of the first piston—and a support ring located about the periphery of the first piston between the first and second seals, wherein the support ring is movable with respect to the piston; the support ring being located in a channel disposed about the periphery of the first piston, and is configured to be movable within the channel; a single power source supplying power to the first and second pistons which move their respective first and second jaws; the single power source being a fluid power source; fluid ports provided on the first and second end caps—a base that extends between the first and second end caps that further comprises open and close fluid passages that are in communication with their respective open and close ports, and are in fluid communication with the first and second pistons to move the first and second jaws—and at least two power supplies to independently control the first and second jaws, wherein a first power supply distributes power to the first jaw and the second power supply distributes power to the second jaw; and the base comprising a key configured to engage a receiver located on the first end cap for selective positioning of the base relative thereto.
An illustrative embodiment of a method of manufacturing a long travel gripper is also provided. This method comprises the steps of: providing first and second end caps and at least one guide rail longitudinally extending between the first and second end caps; and, forming first and second jaws by extruding the jaws, wherein at least one cavity is formed in each jaw by extruding the same.
In the above and other illustrative embodiments, the method of manufacturing the long travel gripper also comprises: the cavity being configured to receive a piston; the first and second caps being attachable to an end of their respective first and second jaws and configured to cover at least a portion of an opening that is part of the extruded cavity formed in each of the first and second jaws; and forming a guide rail passage by extruding it in the first and second jaws; and applying a bearing surface to the guide rail passage in each of the first and second jaws.
Another illustrative embodiment of a method of manufacturing a long travel gripper is provided, the method comprises the steps of: providing first and second end caps, a plurality of guide rails longitudinally extending between the first and second end caps, and first and second jaws; extruding a base member; wherein at least one fluid passage is longitudinally formed in the base member during extruding the base member; and locating the base member between the first and second end caps.
In the above and other illustrative embodiments, the method of manufacturing the long travel gripper also comprises: the at least one fluid passage in the base being extruded the length of base member; the at least one fluid passage in the base forming a first fluid passage and a second air passage, wherein fluid is supplied to the first and second fluid passages to move the first and second jaws between open and closed positions; and providing a piston assembly for moving the jaws between open and closed positions, wherein the piston assembly comprises a piston rod that is formed by extruding it along with at least first and second collinear passages therein.
Additional features and advantages of the long travel gripper assembly will become apparent to those skilled in the art upon consideration of the several embodiments disclosed in the following detailed descriptions exemplifying the best mode of carrying out the long travel gripper assembly as presently perceived.
Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates embodiments of the long travel gripper, and such exemplification is not to be construed as limiting the scope of the long travel gripper in any manner.